Base64 Encode / Decode — TypeScript source

Encode text to Base64 or decode it back. UTF-8 safe, runs entirely in your browser, with a shareable link to your exact input.

This is the TypeScript implementation — the same logic the interactive tool runs, in a shareable, citable form.

Open the interactive tool →

// UTF-8 safe Base64 (handles multibyte correctly, no spread-arg limit).
export function b64encode(str: string): string {
  const bytes = new TextEncoder().encode(str);
  let bin = '';
  for (const b of bytes) bin += String.fromCharCode(b);
  return btoa(bin);
}

export function b64decode(b64: string): string {
  const bin = atob(b64.replace(/\s+/g, ''));
  const bytes = new Uint8Array(bin.length);
  for (let i = 0; i < bin.length; i++) bytes[i] = bin.charCodeAt(i);
  return new TextDecoder().decode(bytes);
}

Also available in 13 other languages

Every CosmoDev tool ships its pure logic in TypeScript (web) and Go (CLI), with authored implementations in a dozen-plus languages — the same contract, ported. Compare all languages side by side →